(1) Field of the Invention
The present invention relates to a pressure switch and a method of manufacture thereof and, more specifically, to a pressure switch which has a vent communicating the interior with the exterior of the switch and which has a means to effectively prevent an outflow of engine oil through the vent. The invention also relates to a method of manufacturing such a pressure switch.
(2) Description of the Prior Art
A type of pressure switch has often been used which, when a pressure in an engine reaches a set pressure, closes its contact to generate, for example, an engine control signal.
Such a conventional pressure switch comprises an electrically conductive body and an insulating cap, with a diaphragm which deforms according to pressure installed inside the conductive body.
When a pressure in the engine is not high enough to activate the diaphragm, the contact is on. As the engine pressure increases and the diaphragm is activated, the contact is turned off, issuing a signal indicating that the pressure has exceeded the set value.
This pressure switch also has a vent formed in the insulating cap that communicates the interior with the exterior of the switch to draw air into the switch in order to minimize possible changes in the activating point of the diaphragm that may be caused by temperature changes.